Machines, including wheel loaders, on- and off-highway haul trucks, vocational trucks, motor graders, and other types of heavy equipment generally include a brake assembly operatively connected to each traction device of the machine. Typical brake assemblies include a plurality of friction discs connected to rotate with an axle of the machine, a plurality of separator plates disposed between adjacent friction discs and rotationally constrained at their periphery by a brake housing, and a piston configured to push the friction discs and separator plates together, thereby generating frictional torque between the plates and discs that retards rotation of the axle. Brake assemblies that are cooled via fluid are known as wet brake assemblies.
Over time, the friction discs and/or separator plates wear and need to be replaced in order for the brake assembly to continue to provide a desired level of braking. Replacing the plates before they are completely worn increases the operating cost of the machine. Delaying replacement of the plates can result in reduced braking and/or damage to the brake assembly. Unfortunately, it may not always be known when the plates and/or discs are fully worn and should be replaced. This may be especially true for wet brake assemblies, as the plates and discs are enclosed and cannot be readily observed without disassembly.
The friction discs and/or separator plates can also be damaged before they are completely worn. In particular, if the brake assemblies are actuated excessively and/or without appropriate cooling, the plates can overheat. When the plates and discs overheat, they can warp from the elevated temperatures, causing the brake assemblies to function poorly or not all. Similar to worn plates or discs, damaged plates and discs can be difficult to detect.
One way to determine when the friction discs and/or separator plates of a wet brake assembly are worn is disclosed in U.S. Pat. No. 4,186,882 issued to Khuntia et al. on Feb. 5, 1980 (“the '882 patent”). Specifically, the '882 patent discloses an oil cooled disc brake having a disc pack enclosed within a housing. Wear of the disc pack can be checked by a service technician without requiring disassembly of the brake, by insertion of a pin into an existing boss of the housing. When the service brake piston is actuated to squeeze a new disc pack, an extension of the pin from the boss is measured. The measurement is then stamped on the outside of the housing for future reference and the boss is plugged. To measure wear at any time thereafter; the plug is removed, the brakes are actuated, and the pin is reinserted. The extension distance is re-measured and compared with the original measurement. If the difference between measurements is within a specified wear limit, the disc pack need not be replaced. If the difference exceeds the specified wear limit, new plates are required.
Although the method disclosed in the '882 patent may be acceptable for some applications, it may also be limited. In particular, the method may not provide an indication of failure that is premature to fully worn conditions. Further, the method may be time intensive and complicated, providing opportunity for error.
The brake assembly of the present disclosure is directed toward solving one or more of the problems set forth above and/or other problems of the prior art.